#include<bits/stdc++.h>
#define fore(i,l,r)	for(int i=(int)(l);i<(int)(r);++i)
#define fi first
#define se second
#define endl '\n'
#define ull unsigned long long
#define ALL(v) v.begin(), v.end()
#define Debug(x, ed) std::cerr << #x << " = " << x << ed;

const int INF=0x3f3f3f3f;
const long long INFLL=1e18;

typedef long long ll;

template <typename T>
struct Fenwick {
    int n;
    std::vector<T> a;

    Fenwick(int n_ = 0) {
        init(n_);
    }
    
    void init(int n_) {
        n = n_;
        a.assign(n + 5, T{});
    }

    void update(int p, const T &v) { //在位置 p 加 v
        while(p <= n){
            a[p] += v;
            p += p & -p;
        }
    }
    
    T query(int p) {
        T ans{};
        while(p > 0){
            ans += a[p];
            p -= p & -p;
        }
        return ans;
    }

    T rangeSum(int l, int r) {
        return query(r) - query(l - 1); //前缀和
    }

    int find_first(T sum){ //找到第一个 query(p) >= sum 的位置 p
        int p = 0;
        T val = 0;
        for(int i = std::__lg(n); i >= 0; --i)
            if((p | 1 << i) <= n && val + a[p | 1 << i] < sum){
                p |= 1 << i;
                val += a[p];
            }
        return p + 1;
    }

    int find_last(T sum){ //找到最后一个 query(p) <= sum 的位置 p
        int p = 0;
        T val = 0;
        for(int i = std::__lg(n); i >= 0; --i)
            if((p | 1 << i) <= n && val + a[p | 1 << i] <= sum){
                p |= 1 << i;
                val += a[p];
            }
        return p;
    }
};

int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    int t;
    std::cin >> t;
    while(t--){
        int n;
        ll k;
        std::cin >> n >> k;
        std::vector<int> a(n + 1);
        std::map<int, int> mp;
        std::vector<int> b;
        fore(i, 1, n + 1){
            std::cin >> a[i];
            a[i] -= i;
            b.push_back(a[i]);
        }
        std::sort(ALL(b));
        b.erase(unique(ALL(b)), b.end());
        std::vector<int> o(n + 1);
        for(auto x : b) mp[x] = mp.size() + 1;
        fore(i, 1, n + 1) o[i] = mp[a[i]];

        int num = mp.size();
        Fenwick<int> fenc(num);
        Fenwick<ll> fens(num);

        auto check = [&](int j) -> bool {
            fenc.update(o[j], 1);
            fens.update(o[j], a[j]);
            int m = fenc.query(num);
            int med = fenc.find_first((m + 1) / 2);
            int m1 = fenc.query(med);
            ll s1 = fens.query(med);
            if(1ll * m1 * b[med - 1] - s1 + fens.query(num) - s1 - 1ll * (m - m1) * b[med - 1] <= k)
                return true;

            fenc.update(o[j], -1);
            fens.update(o[j], -a[j]);
            return false;
        };

        int l = 1, r = 0;
        int ans = 1;
        while(l <= n){
            while(r < n && check(r + 1)){
                ++r;
            }
            ans = std::max(ans, r - l + 1);
            fenc.update(o[l], -1);
            fens.update(o[l], -a[l]);
            ++l;
        }

        std::cout << ans << endl;
    }
    
    return 0;
}